Fuel supply system for an internal combustion engine

Abstract

A fuel supply system for a marine propulsion system having an electronically controlled fuel injection system eliminates the need for a vapor separator. The system pumps an excessive amount of fuel through a plumbed fuel supply loop and cools recirculated fuel to cool all the components in the plumbed fuel supply loop, i.e. a continuous duty, constant displacement fuel pump; a pressure regulator; and a water separating fuel filter. Recirculated fuel flows from the pressure regulator to the water separating fuel filter as does make-up fuel from a fuel tank. The fuel stream from the water separating fuel filter flows to the low-pressure side of the fuel pump, which pumps the fuel through the plumb fuel supply loop. A fuel injection portion of the fuel flows to the engine for combustion, while the remaining portion of the fuel is recirculated. The recirculated portion of the fuel is cooled, preferably using a water-cooled heat exchanger. The cooled, recirculated fuel passes through the pressure regulator and repeats recirculation to the water separating fuel filter.

We claim: 
     
       1. In a marine propulsion system, a method of supplying fuel from a main fuel tank to an internal combustion engine comprising the steps of: providing a plumbed fuel supply loop through which a stream of fuel flows,   continuously pumping the stream of fuel flowing through the plumbed fuel supply loop with a fuel pump, the fuel pump displacing a relatively fixed volume of liquid fuel;   cooling the fuel stream flowing through the plumbed fuel supply loop with a fuel cooler;   supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   recirculating a remaining portion of the fuel stream which is not supplied to the engine for combustion through the plumbed fuel supply loop at a location in the plumbed fuel supply loop upstream of the fuel pump and cooler;   providing make-up fuel from a main vehicle fuel tank to replenish the recirculated fuel stream flowing through the plumbed fuel supply loop;   providing the replenished recirculated fuel stream through the plumbed fuel supply loop to a low-pressure side of the fuel pump without accumulating the replenished recirculated fuel stream in a vapor separator; and   filtering the fuel stream flowing through the plumbed fuel supply loop through a water separating fuel filter at a location in the plumbed fuel supply loop upstream of the fuel pump and downstream of the location where the remaining portion of the fuel stream that was not supplied to the engine is recirculated through the plumbed fuel supply loop and also downstream of the location where the make-up fuel is provided to replenish the recirculated fuel flow through the plumbed fuel supply loop.   
     
     
       2. In a marine propulsion system, a method of supplying fuel from a main fuel tank to an internal combustion engine comprising the steps of: providing a plumbed fuel supply loop through which a stream of fuel flows;   continuously pumping the stream of fuel flowing through the plumbed fuel supply loop with a fuel pump, the fuel pump displacing a relatively fixed volume of liquid fuel;   cooling the fuel stream flowing through the plumbed fuel supply loop with a fuel cooler;   supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   recirculating a remaining portion of the fuel stream which is not supplied to the engine for combustion through the plumbed fuel supply loop at a location in the plumbed fuel supply loop upstream of the fuel pump and cooler;   providing make-up fuel from a main vehicle fuel tank to replenish the recirculated fuel stream flowing through the plumbed fuel supply loop;   providing the replenished recirculated fuel stream through the plumbed fuel supply loop to a low-pressure side of the fuel pump without accumulating the replenished recirculated fuel stream in a vapor separator; and   wherein the fuel stream flowing through the plumbed fuel supply loop is cooled downstream of the fuel pump and upstream of the location in which the fuel injection portion of the fuel stream is supplied to the engine for combustion.   
     
     
       3. A method as recited in claim 2 further comprising the step of: regulating the pressure of the fuel injection portion of the fuel stream supplied to the engine for combustion using a pressure regulator.   
     
     
       4. A method as recited in claim 2 wherein: the fuel cooler is a heat exchanger that receives an engine cooling fluid before the engine cooling fluid is used to cool the engine; and   the fuel stream is cooled by passing the fuel stream through the heat exchanger.   
     
     
       5. A method as recited in claim 2 wherein: the fuel cooler is a heat exchanger;   the fuel stream is cooled by passing the fuel stream through the heat exchanger; and   the heat exchanger uses sea water flowing through the heat exchanger to absorb heat from the fuel stream.   
     
     
       6. In a marine propulsion system, a method of supplying fuel from a main fuel tank to an internal combustion engine comprising the steps of: providing a plumbed fuel supply loop through which a stream of fuel flows:   continuously pumping the stream of fuel flowing through the plumbed fuel supply loop with a fuel pump, the fuel pump displacing a relatively fixed volume of liquid fuel;   cooling the fuel stream flowing through the plumbed fuel supply loop with a fuel cooler;   supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   recirculating a remaining portion of the fuel stream which is not supplied to the engine for combustion through the plumbed fuel supply loop at a location in the plumbed fuel supply loop upstream of the fuel pump and cooler;   providing make-up fuel from a main vehicle fuel tank to replenish the recirculated fuel stream flowing through the plumbed fuel supply loop;   providing the replenished recirculated fuel stream through the plumbed fuel supply loop to a low-pressure side of the fuel pump without accumulating the replenished recirculated fuel stream in a vapor separator; and   insulating the fuel pump and the fuel cooler from engine generated heat by placing the fuel pump and the fuel cooler within a common heat insulating structure.   
     
     
       7. A method as recited in claim 6 further comprising the step of: providing an additional heat sink in conjunction with the heat insulating structure used to insulate the fuel pump and the fuel cooler, the heat sink being cooled by the fuel cooler when the engine is operating and absorbing engine generated heat when the engine is not operating.   
     
     
       8. A method as recited in claim 3 further comprising the step of: insulating the pressure regulator from engine generated heat by placing the pressure regulator within a heat insulating structure.   
     
     
       9. A method as recited in claim 1 further comprising the step of: insulating the water separating fuel filter from engine generated heat by placing the water separating fuel filter within a heat insulating structure.   
     
     
       10. A method as recited in claim 3 wherein the pressure of the fuel injection portion of the fuel stream supplied to the engine is maintained at a preselected amount of over a reference intake manifold pressure. 
     
     
       11. In a marine propulsion system having an internal combustion engine mounted to joists in a boat and covered by an engine box, a method of supplying fuel to the engine from a boat fuel tank comprising the steps of: providing a plumbed fuel supply loop through which a stream of fuel flows;   continuously pumping the stream of fuel flowing through the plumbed fuel supply loop with a fuel pump that displaces a relatively fixed volume of liquid fuel from a low-pressure side of the pump to a high-pressure side of the pump;   filtering the fuel stream flowing through the plumbed fuel supply loop through a water separating fuel filter upstream of the fuel pump;   cooling the fuel stream flowing through the plumbed fuel supply loop downstream of the fuel pump;   supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   regulating the pressure of the fuel injection portion of the fuel stream flowing to the engine for combustion;   recirculating a remaining portion of the fuel stream which is not supplied to the engine for combustion through the plumbed fuel supply loop at a location upstream of the water separating fuel filter; and   providing make-up fuel from the boat fuel tank to the water separating fuel filter to replenish the recirculated fuel stream flowing through the plumbed fuel supply loop.   
     
     
       12. A fuel supply system for an internal combustion engine comprising: a fuel tank;   a plumbed fuel supply loop including a main fuel line and a return fuel line;   a high-volume, high-pressure fuel pump located in the main fuel line that continuously pumps a stream of fuel through the plumbed fuel supply loop, the fuel pump displacing a relatively constant volume of fuel;   a heat exchanger that cools the stream of fuel flowing through the plumbed fuel supply loop;   means for supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   a pressure regulator located in the plumbed fuel supply loop downstream of the fuel pump that regulates the pressure of the fuel injection portion of the fuel stream flowing to the engine for combustion;   a return fuel line connected to the pressure regulator that recirculates a remaining portion of the fuel stream that is not supplied to the engine for combustion to the plumbed fuel supply loop upstream of the fuel pump and upstream of the heat exchanger; and   means for providing make-up fuel from the fuel tank to the fuel stream flowing through the plumbed fuel supply loop to replenish the recirculated fuel stream;   a water separating fuel filter that receives recirculated fuel from the fuel return line and outputs filtered fuel to the main fuel line at a location upstream of the fuel pump; and   wherein said means for providing make-up fuel from the fuel tank comprises a fuel tank supply line that supplies fuel from the fuel tank directly to an upstream side of the water separating fuel filter.   
     
     
       13. A fuel supply system for an internal combustion engine comprising: a fuel tank;   a plumbed fuel supply loop including a main fuel line and a return fuel line, a high-volume, high-pressure fuel pump located in the main fuel line that continuously pumps a stream of fuel through the plumbed fuel supply loop, the fuel pump displacing a relatively constant volume of fuel;   a heat exchanger that cools the stream of fuel flowing through the plumbed fuel supply loop:   means for supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump:   a pressure regulator located in the plumbed fuel supply loop downstream of the fuel pump that regulates the pressure of the fuel injection portion of the fuel stream flowing to the engine for combustion;   a return fuel line connected to the pressure regulator that recirculates a remaining portion of the fuel stream that is not supplied to the engine for combustion to the plumbed fuel supply loop upstream of the fuel pump and upstream of the heat exchanger;   means for providing make-up fuel from the fuel tank to the fuel stream flowing through the plumbed fuel supply loop to replenish the recirculated fuel stream;   a water separating fuel filter that receives recirculated fuel from the fuel return line and outputs filtered fuel to the main fuel line at a location upstream of the fuel pump.   
     
     
       14. A fuel supply system as recited in claim 13 wherein the fuel return line is connected directly to an upstream side of the water separating fuel filter. 
     
     
       15. A fuel supply system as recited in claim 13 further comprising a heat insulated housing that contains the water separating fuel filter, the heat insulating housing being mounted to the engine. 
     
     
       16. A fuel supply system as recited in claim 15 wherein the insulated housing comprises: an insulating cup member including a bottom wall and a side wall that is substantially perpendicular to the bottom wall and circumferentially surrounds the water separating fuel filter except for an open backside portion corresponding to a backside of the water separating fuel filter facing the engine;   an insulating back member that engages the insulating cup member and covers the open backside portion of the insulating cup member, the insulating back member being mounted to the engine; and   an insulating cap that engages a top edge of the insulating cup member and a top edge of the insulating back member.   
     
     
       17. A fuel supply system as recited in claim 16 wherein an air gap of at least 0.20 inches exists between the water separating fuel filter and the insulating cup member of the insulated housing. 
     
     
       18. A fuel supply system for an internal combustion engine comprising: a fuel tank;   a plumbed fuel supply loop including a main fuel line and a return fuel line;   a high-volume, high-pressure fuel pump located in the main fuel line that continuously pumps a stream of fuel through the plumbed fuel supply loop, the fuel pump displacing a relatively constant volume of fuel;   a heat exchanger that cools the stream of fuel flowing through the plumbed fuel supply loop;   means for supplying a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the engine for combustion, the amount of the fuel injection portion under all operating conditions being substantially less than the amount of fuel pumped by the fuel pump;   a pressure regulator located in the plumbed fuel supply loop downstream of the fuel pump that regulates the pressure of the fuel injection portion of the fuel stream flowing to the engine for combustion;   a return fuel line connected to the pressure regulator that recirculates a remaining portion of the fuel stream that is not supplied to the engine for combustion to the plumbed fuel supply loop upstream of the fuel pump and upstream of the heat exchanger;   means for providing make-up fuel from the fuel tank to the fuel stream flowing through the plumbed fuel supply loop to replenish the recirculated fuel stream;   an insulated packaging system that contains the fuel pump and the heat exchanger and insulates the fuel pump and heat exchanger from engine generated heat.   
     
     
       19. A fuel supply system as recited in claim 18 wherein the insulated packaging system further contains the pressure regulator, and also insulates the pressure regulator from engine generated heat. 
     
     
       20. A fuel supply system as recited in claim 18 further comprising an additional heat sink that is contained within the insulated packaging system. 
     
     
       21. A fuel supply system as recited in claim 18 further comprising a bracket that attaches the insulated packaging system to the engine, the bracket including a lower plate that extends underneath a bottom surface of the insulated packaging system and shields the bottom surface of the insulated packaging system. 
     
     
       22. A fuel supply system as recited in claim 21 wherein the bracket further includes a face plate and an upper plate to shield the insulated packaging system from radiant heat from the engine, the face plate extending vertically upward from the lower plate and the upper plate extending diagonally upward from a top edge of the face plate. 
     
     
       23. A fuel supply system as recited in claim 18 further comprising an insulated housing which contains a water separating fuel filter. 
     
     
       24. A fuel supply system as recited in claim 23 wherein the engine has a V style engine block and the fuel pump and heat exchanger within the insulated packaging system are mounted to a first side of the V style engine block and the water separating fuel filter within the insulated housing is mounted to a second side of the V style engine block. 
     
     
       25. A fuel supply system as recited in claim 24 wherein: the main fuel line is connected to a downstream side of the water separating fuel filter and the fuel return line is connected to an upstream side of the water separating fuel filter;   a sea water pump is mounted to the engine; and   the main fuel line and the fuel return line loop from the second side of the V style engine block to the first side of the V style engine block by passing below a lowermost height of the sea water pump.   
     
     
       26. A fuel supply system as recited in claim 24 wherein: the insulated packaging system further contains the pressure regulator;   the main fuel line is connected between a downstream side of the water separating fuel filter and an upstream side of the fuel pump;   the return fuel line is connected between a downstream side of the pressure regulator and an upstream side of the water separating fuel filter; and   the insulated packaging system containing the fuel pump, the heat exchanger and the pressure regulator and the water separating fuel filter contained in the insulated housing are removable from the engine block without disconnecting the main fuel line from the water separating fuel filter or the fuel pump or disconnecting the return fuel line from the pressure regulator or the water separating fuel filter.   
     
     
       27. A fuel supply system as recited in claim 24 wherein: the first side of the V style engine block includes a first engine mount that is used to mount the first side of the engine block to a mounting bracket attached to the boat and the second side of the V style engine block includes a second engine mount that is used to mount the second side of the engine block to a mounting bracket that is attached to the boat; and   at least a portion of the insulated packaging system containing the fuel pump and the heat exchanger is located below the first engine mount and at least a portion of the insulated housing containing the water separating fuel filter is located below the second engine mount.   
     
     
       28. In a marine propulsion system having an internal combustion engine mounted to joists in a boat and covered by an engine box, a fuel supply system comprising: a fuel tank;   a plumbed fuel supply loop including a main fuel line and a return fuel line;   a high-volume, high-pressure fuel pump that pumps a stream of fuel continuously through the plumbed fuel supply loop, the fuel pump receiving fuel from the main fuel line and displacing a relatively constant volume of fuel;   a heat exchanger that cools the fuel stream flowing through the plumbed fuel supply loop at a location in the fuel supply loop downstream of the fuel pump;   an electronic fuel injection system for the engine;   an engine fuel supply line that supplies a fuel injection portion of the fuel stream flowing through the plumbed fuel supply loop to the electronic fuel injection system;   a pressure regulator that regulates the pressure of the fuel injection portion of the fuel stream supplied to the electronic fuel injection system through the engine fuel supply line;   a fuel return line that recirculates the remaining portion of the fuel stream that is not supplied to the electronic fuel injection system to the fuel supply loop wherein the amount of the fuel injection portion under all operating conditions is substantially less than the amount of fuel pumped by the fuel pump;   a make-up fuel line from the fuel tank through which fuel is supplied from the fuel tank to replenish the recirculated fuel stream; and   a water separating fuel filter that receives fuel flowing through the fuel return line and fuel flowing through the make-up fuel line, and outputs fuel into the main fuel line.